NIH Image

NIH Image has painting and image manipulation tools, a macro language, tools for measuring areas, distances and angles, and for counting things. Using a frame grabber card, it can record sequences of images to be played back as a movie. It can invoke user-defined convolution matrix filters, such as Gaussian. It can import raw data in tab-delimited ASCII, or as 1 or 2-byte quantities. It also does histograms and even 3-D plots. It is limited to 8-bits/pixel, though the 8 bits map into a color lookup table. It runs on any Mac that has a 256-color screen.